This invention is in the technical field of aberration correction for an optical instrument such as a deformable mirror and a deformable lens.
Deformable mirrors with actuators for controlling deformation were disclosed by John Hardy (xe2x80x9cActive Optics: A New Technology for the Control of Light,xe2x80x9d IEEE, Vol. 60, No. 6 (1978)). U.S. Pat. No. 5,037,184 issued Aug. 6, 1991 to Ealey describes a thin-membrane mirror supported directly by many high-stiffness actuators such as PZT actuators. Since commercially available actuators of this kind are at least about 80 mm in length, such actuator attachment mechanisms are not practical in optical designs requiring mirrors and lenses to be disposed with smaller gaps therebetween.
It is therefore an object of this invention to reduce the amount of space needed to facilitate wavefront aberration correction.
A wavefront aberration correction system embodying this invention for an adaptive optic such as a deformable mirror may be characterized not only as comprising a plurality of correction units each comprising an actuator, a force-applying member attached to the back surface of the adaptive optic at a specified position, and a force-communicating device connecting the actuator with the force-applying member but also wherein the actuator is disposed outside the perimeter of the adaptive optic. With the actuators thus disposed outside the perimeter of the adaptive optic, instead of directly behind its back surface, the envelope size behind can be made compact, allowing for a smaller gap behind the adaptive optic (that is, between two optics) in an optical design. Another advantage of placing the actuators outside the perimeter of the adaptive optic is that thermal effects of the actuators on the adaptive optic can be reduced.
The force-applying members may preferably be a flexure which is stiff only in the direction in which the force is required such that a linear force may be applied to the adaptive optic. The force-communicating device of each correction unit serves to redirect or xe2x80x9cbendxe2x80x9d the actuating force of the actuator into a direction perpendicular to the back surface of the adaptive optic. For this purpose, the force-communicating device according to this invention may include a lever or an L-shaped bell-crank. It is preferable that the lever or the bell-crank of the force-communicating device be supported rotatably around a flexural pivot.
A method of this invention for correcting wavefront aberration of an adaptive optic may be characterized as providing a correction system as described above and controlling its actuators.